Same Type Attack Bonus

Same Type Attack Bonus, more commonly known as STAB increases an attack of the same type as the Pokémon using it by 50%, this results in an increase of damage by 50% also.

'STAB' does not apply to attacks that exert a specific amount of damage each turn and thus does not follow the typical battle formula (For example, if Dragonite was using Dragon Rage then the move would not receive any attack bonus), another example of this is Seismic Toss.

The Same Type Attack Bonus was introduced in Generation I and has remained unchanged since.

Hidden Power does in fact receive the attack bonus only if the IV's cause the attack to be the same type as the user. For example if a Fire Type Pokémon used Hidden Power Fire then STAB would affect the damage inflicted. However, even though this move is classified as a Normal Type attack, normal type Pokemon do not receive the bonus because the game data causes the typing match for the attack not to have the affects of a normal type move. The only way this proves incorrect is is the Normal Type is dueled with another type, know the move Camouflage, or have either the Normalize ability or Color Change ability.